Chewing Maintains Hippocampus-Dependent Cognitive Function

Chen, Huayue; Iinuma, Mitsuo; Onozuka, Minoru; Kubo, Kin‐ya

doi:10.7150/ijms.11911

Cited by 100 publications

(117 citation statements)

References 79 publications

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“…We and others have already shown that tooth extraction in rodents can also induce functional and structural changes in both glial and neuronal cells within brain regions involved in processing orofacial sensory and motor functions as well as cognitive and emotional behaviors (Avivi-Arber et al, 2014, 2015; Varathan et al, 2014; Chen et al, 2015; Watase et al, 2016). High resolution sMRI in rodents can provide an excellent readout of anatomical brain changes in mice following nerve injury, housing in an enriched environment, or maze training and such changes are also associated with cellular and molecular changes (Seminowicz et al, 2009; Lerch et al, 2011b; Cahill et al, 2015; Scholz et al, 2015a).…”

Section: Introductionmentioning

confidence: 96%

Widespread Volumetric Brain Changes following Tooth Loss in Female Mice

et al. 2017

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Tooth loss is associated with altered sensory, motor, cognitive and emotional functions. These changes vary highly in the population and are accompanied by structural and functional changes in brain regions mediating these functions. It is unclear to what extent this variability in behavior and function is caused by genetic and/or environmental determinants and which brain regions undergo structural plasticity that mediates these changes. Thus, the overall goal of our research program is to identify genetic variants that control structural and functional plasticity following tooth loss. As a step toward this goal, here our aim was to determine whether structural magnetic resonance imaging (sMRI) is sensitive to detect quantifiable volumetric differences in the brains of mice of different genetic background receiving tooth extraction or sham operation. We used 67 adult female mice of 7 strains, comprising the A/J (A) and C57BL/6J (B) strains and a randomly selected sample of 5 of the 23 AXB-BXA strains (AXB1, AXB4, AXB24, BXA14, BXA24) that were produced from the A and B parental mice by recombinations and inbreeding. This panel of 25 inbred strains of genetically diverse inbred strains of mice is used for mapping chromosomal intervals throughout the genome that harbor candidate genes controlling the phenotypic variance of any trait under study. Under general anesthesia, 39 mice received extraction of 3 right maxillary molar teeth and 28 mice received sham operation. On post-extraction day 21, post-mortem whole-brain high-resolution sMRI was used to quantify the volume of 160 brain regions. Compared to sham operation, tooth extraction was associated with a significantly reduced regional and voxel-wise volumes of cortical brain regions involved in processing somatosensory, motor, cognitive and emotional functions, and increased volumes in subcortical sensorimotor and temporal limbic forebrain regions including the amygdala. Additionally, comparison of the 10 BXA14 and 21 BXA24 mice revealed significant volumetric differences between the two strains in several brain regions. These findings highlight the utility of high-resolution sMRI for studying tooth loss-induced structural brain plasticity in mice, and provide a foundation for further phenotyping structural brain changes following tooth loss in the full AXB-BXA panel to facilitate mapping genes that control brain plasticity following orofacial injury.

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Section: Introductionmentioning

confidence: 96%

Widespread Volumetric Brain Changes following Tooth Loss in Female Mice

et al. 2017

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“…Chewing is also an effective stress-coping behavior [50][51][52]. Recent basic and clinical investigations have shown that chewing may alleviate stress-induced responses, such as increases in noradrenaline turnover in rat hypothalamus, and impaired spatial memory due to an increase in GC receptor expression in the hippocampus [51,52].…”

Section: Active Mastication Ameliorates Chronic Stressinduced Bone Lossmentioning

confidence: 99%

Chronic Psychological Stress as a Risk Factor of Osteoporosis

Chen

Adachi

Hayashi

et al. 2015

J UOEH

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: Osteoporosis, the most common metabolic skeletal disease, is characterized by decreased bone mass and deteriorated bone quality, leading to increased fracture risk. With the aging of the population, osteoporotic fracture is an important public health issue. Organisms are constantly exposed to various stressful stimuli that affect physiological processes. Recent studies showed that chronic psychological stress is a risk factor for osteoporosis by various signaling pathways. The purpose of this article is to review the recent progress of the association between chronic psychological stress and osteoporosis. Increasing evidence confirms the physiological importance of the central nervous system, especially the hypothalamus, in the regulation of bone metabolism. Both animal and human studies indicate that chronic psychological stress induces a decrease of bone mass and deterioration of bone quality by influencing the hypothalamic-pituitary-adrenocortical (HPA) axis, sympathetic nervous system, and other endocrine, immune factors. Active mastication, proven to be an effective stress-coping behavior, can attenuate stress-induced neuroendocrine responses and ameliorate stress-induced bone loss. Therefore, active mastication may represent a useful approach in preventing and/or treating chronic stress-associated osteoporosis. We also discuss several potential mechanisms involved in the interaction between chronic stress, mastication and osteoporosis. Chronic stress activates the HPA axis and sympathetic nervous system, suppresses the secretion of gonadal hormone and growth hormone, and increases inflammatory cytokines, eventually leading to bone loss by inhibiting bone formation and stimulating bone resorption.

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“…Unfortunately, neither paper showed scatter plots that would have provided clues about the behavioral relevance of the variation in BrdU-labeled neurons and the behavior scores. Nonetheless, it would be interesting to investigate whether strong chewing in elderly humans might convey the same mental benefits as other forms of more demanding physical exercise [Chen et al, 2015].…”

Section: Research Findings In Ahn and Their Perception By The Publicmentioning

confidence: 99%

Adult Neurogenesis in Mammals: Variations and Confusions

Lipp

Bonfanti

2016

Brain Behav Evol

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Mammalian adult neurogenesis has remained enigmatic. Two lines of research have emerged. One focuses on a potential repair mechanism in the human brain. The other aims at elucidating its functional role in the hippocampal formation, chiefly in cognitive processes; however, thus far it has been unsuccessful. Here, we try to recognize the sources of errors and conceptual confusion in comparative studies and neurobehavioral approaches with a focus on mice. Evolutionarily, mammalian adult neurogenesis appears as protracted juvenile neurogenesis originating from precursor cells in the secondary proliferation zones, from where newly formed cells migrate to target regions in the forebrain. This late developmental process is downregulated differentially in various brain structures depending on species and age. Adult neurogenesis declines substantially during early adulthood and persists at low levels into senescence. Short-lasting episodes in proliferation or reduction of adult neurogenesis may reflect a multitude of factors, and have been studied chiefly in mice and rats. Comparative studies face both species-specific variations in staining and technical abilities of laboratories, lacking quantification of important reference measures (e.g. granule cell number) and evaluation of maturational markers whose persistence might be functionally more relevant than proliferation rates. Likewise, the confusion about the functional role of variations in adult hippocampal neurogenesis has many causes. Prominent is an inferential statistical approach, usually with low statistical power. Interpretation is complicated by multiple theories about hippocampal function, often unrealistically extrapolating from humans to rodents. We believe that the field of mammalian adult neurogenesis needs more critical thinking, more sophisticated hypotheses, better statistical, technical and behavioral approaches, and a broader conceptual perspective incorporating comparative aspects rather than neglecting them.

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Chewing Maintains Hippocampus-Dependent Cognitive Function

Cited by 100 publications

References 79 publications

Widespread Volumetric Brain Changes following Tooth Loss in Female Mice

Widespread Volumetric Brain Changes following Tooth Loss in Female Mice

Chronic Psychological Stress as a Risk Factor of Osteoporosis

Adult Neurogenesis in Mammals: Variations and Confusions

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